gadm: Maps of Vietnam

Description Usage Arguments Details Value Note Author(s) Source Examples

Description

Generates a country or provinces map of Vietnam for a given date and resolution.

Usage

1
2
gadm(date = "2015-01-01", level = c("provinces", "country"),
  resolution = c("low", "high"), merge_hanoi = FALSE)

Arguments

date

either text in the "YYYY-MM-DD" format (for example "2015-01-17" for the 17th of January 2017), or a numeric format of the year (for example 2015). By default "2015-01-01".

level

text ("country" or "provinces"). By default "provinces".

resolution

text ("low" or "high"). By default "low".

merge_hanoi

boolean indicating whether the province of Ha Noi should be merged with the province of Ha Son Binh (before 1992) or the province of Ha Tay (after 1991).

Details

This function generates a country or provinces map of Vietnam at a given date, and for a given resolution. Indeed, the delimitations of Vietnamese provinces have changed through the history with the number of provinces increasing from 40 in 1979 to 63 in 2008. Most of the events are province splits and one merging. Changes is provinces boundaries occured on the 1st of January of 1979, 1990, 1991, 1992, 1997, 2004 and 2008.

The maps generated for a time after 2008 contained different information:

Column Names Description
province name of the province in English
region name of the ecologic region in English
color_ecologic color associated with the ecologic region
region_economic name of the region economic in English
color_economic color associated with the economic region
geometry list-column with geometries

Wheras the map generated for a time before 2008, only the columns "province" and "geometry".

Value

An object of class "sf" and "data.frame".

Note

argument merge_hanoi makes a difference only for date before 2008-01-01.

Provinces are plotted in alphabetical order. This is important information to know whenever the user wishes to use these maps to plot covariables.

Author(s)

Marc Choisy

Source

GADM data base from www.gadm.org.

Examples

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
library(sf)

# BASIC USAGE ---------------------------------------------------------------

# Plotting the map of Vietnamese provinces as of today:
pr <- gadm()
plot(st_geometry(pr))
# other way of plotting
plot(pr["province"]) # by default a color key is given

# The same, with random colors:
plot(st_geometry(pr), col = 1:4)

# Plotting only the country boundaries:
vn <- gadm(level = "country")
plot(st_geometry(vn), col = "grey")

# SF TO SP ------------------------------------------------------------------

# The `pr` object is an object of class `sf` and `data.frame`. For more
# complexe analyses, it a be interresting to work with an object of class
# `SpatialPolygonsDataFrame` from the `sp` package:
sp_vn <- sf::as_Spatial(pr$geometry)
sp::plot(sp_vn)


# MORE COMPLEXE EXAMPLE OF VISUALISATION ------------------------------------

# Visualizing the maps of provinces for all the years where their boundaries
# changed:
vn <- lapply(c(1979, 1990:1992, 1997, 2004, 2008), gadm)
opar <- par(mfrow = c(2, 4))
for(i in vn) plot(st_geometry(i))
par(opar)

# ploting the province of Ha Noi before and after 2008, for 2 values of
# resolution:
vn1_low <- gadm(2007)
vn2_low <- gadm(2008)
vn1_high <- gadm(2007, res = "high")
vn2_high <- gadm(2008, res = "high")
opar <- par(mfrow = c(2, 2))
plot(st_geometry(vn1_low[vn1_low$province %in% c("Ha Noi", "Ha Tay"), ]))
title("2007, low resolution")
plot(st_geometry(vn2_low[vn2_low$province == "Ha Noi", ]))
title("2008, low resolution")
plot(st_geometry(vn1_high[vn1_high$province %in% c("Ha Noi", "Ha Tay"), ]))
title("2007, high resolution")
plot(st_geometry(vn2_high[vn2_high$province == "Ha Noi", ]))
title("2008, high resolution")
par(opar)
plot(st_geometry(vn1_low))

# Showing the same thing on the whole map of Vietnam:
plot(st_geometry(vn1_low))
plot(st_geometry(vn1_high[vn1_high$province %in% c("Ha Noi", "Ha Tay"), ]),
     col = c("red","blue"), add=TRUE)
plot(st_geometry(vn2_low))
plot(st_geometry(vn2_high[vn2_high$province == "Ha Noi", ]),
     col = "grey", add = TRUE)

# Here we can see that the 2008 delimitation of the province of Ha Noi is
# more than the merging of the provinces of Ha Tay and Ha Noi:
plot(st_geometry(vn2_high[vn2_high$province == "Ha Noi", ]), col = "grey")
plot(st_geometry(vn1_high[vn1_high$province %in% c("Ha Noi", "Ha Tay"), ]),
     col = c("red", "blue"), add = TRUE)

choisy/gadmVN documentation built on June 4, 2019, 3:12 p.m.